Tutorial by Examples: n

Bash indirection permits to get the value of a variable whose name is contained in another variable. Variables example: $ red="the color red" $ green="the color green" $ color=red $ echo "${!color}" the color red $ color=green $ echo "${!color}" the ...

${parameter:-word} If parameter is unset or null, the expansion of word is substituted. Otherwise, the value of parameter is substituted. $ unset var $ echo "${var:-XX}" # Parameter is unset -> expansion XX occurs XX $ var="" # Parameter is null ...

The semantics for this are similar to that of default value substitution, but instead of substituting a default value, it errors out with the provided error message. The forms are ${VARNAME?ERRMSG} and ${VARNAME:?ERRMSG}. The form with : will error our if the variable is unset or empty, whereas the ...

1. URLByDeletingPathExtension: If the receiver represents the root path, this property contains a copy of the original URL. If the URL has multiple path extensions, only the last one is removed. 2. URLByAppendingPathExtension: Returns a new URL made by appending a path extension to the original U...

The figure contains all the plot elements. The main way to create a figure in matplotlib is to use pyplot. import matplotlib.pyplot as plt fig = plt.figure() You can optionally supply a number, which you can use to access a previously-created figure. If a number is not supplied, the last-create...

To create a JAR containing all of its dependencies, it is possible to use the built-in descriptor format jar-with-dependencies. The following example configures an execution of the Assembly Plugin bound to the package phase, using this built-in descriptor and declaring a main class of com.example: ...

Shortest match: $ a='I am a string' $ echo "${a#*a}" m a string Longest match: $ echo "${a##*a}" string

Shortest match: $ a='I am a string' $ echo "${a%a*}" I am Longest match: $ echo "${a%%a*}" I

First match: $ a='I am a string' $ echo "${a/a/A}" I Am a string All matches: $ echo "${a//a/A}" I Am A string Match at the beginning: $ echo "${a/#I/y}" y am a string Match at the end: $ echo "${a/%g/N}" I am a strinN Replace a pattern wi...

Inheritance is the biggest asset of the POM, where the following can be managed from super POM to child POM. dependencies developers and contributors plugin lists (including reports) plugin executions with matching ids plugin configuration The following enables the inheritance <paren...

The modules of a multi-module project are aggregated from a hierarchical structure. The root pom packing should look like: <packaging>pom</packaging> The following will be the directory structure of the project: |-- sample-app \ `-- pom.xml |-- sample-module-1 | `--...

In [15]: df = pd.DataFrame({"A":[1,1,2,3,1,1],"B":[5,4,3,4,6,7]}) In [21]: df Out[21]: A B 0 1 5 1 1 4 2 2 3 3 3 4 4 1 6 5 1 7 To get unique values in column A and B. In [22]: df["A"].unique() Out[22]: array([1, 2, 3]) In [23]: df[&qu...

Creates a image representing a linear gradient of colors. linear-gradient( 0deg, red, yellow 50%, blue); This creates a gradient going from bottom to top, with colors starting at red, then yellow at 50%, and finishing in blue.

You can take advantage of Apache Maven's powerful features in Eclipse by installing the M2Eclipse feature. Follow these steps to install Maven in Eclipse: Open Eclipse and select Help → Install New Software… In the opened dialog, select the Add... button to add a new repository. Fill ...

For checking whether some object is of a certain class, the (binary) instanceof operator can be used since PHP version 5. The first (left) parameter is the object to test. If this variable is not an object, instanceof always returns false. If a constant expression is used, an error is thrown. The ...

An operator can be used to manipulate the flow of objects from Observable to Subscriber. Observable<Integer> integerObservable = Observable.just(1, 2, 3); // creating a simple Integer observable Subscriber<String> mSubscriber = new Subscriber<String>() { @Override publi...

Following example illustrate the simplest Hello World in groovy using script, place the following code snippet in a file, say helloWorld.groovy println 'Hello World!' How to execute: In the command line, groovy helloWorld.groovy Output: Hello World!

You can use buffers to work with multiple files. When you open a file using :e path/to/file it opens in a new buffer (the command means edit the file). New buffer that holds a temporary copy of the file. You can go to previous buffer with :bp[rev] and next buffer with :bn[ext]. You can go to a...

Commands have one input (STDIN) and two kinds of outputs, standard output (STDOUT) and standard error (STDERR). For example: STDIN root@server~# read Type some text here Standard input is used to provide input to a program. (Here we're using the read builtin to read a line from STDIN.) STDO...

If you want to see the generated bytecode for a Java program, you can use the provided javap command to view it. Assuming that we have the following Java source file: package com.stackoverflow.documentation; import org.springframework.stereotype.Service; import java.io.IOException; import j...